This study was initiated to define the prevalence of specific viral diseases in the Center colonies supplying monkeys for SIV research. We have surveyed the rhesus and pigtailed macaque breeding colonies for the presence of herpes B, SRV, and STLV-I in 1994 and 1995. Animals were bled at the time of inventory to check for the presence of antibody to these viruses and for culture of SRV. PCR for detection of SRV was also performed this year using primers developed by Dr. Traina-Dorge. In 1994, a total of 823 animals were tested, 56% were positive for herpes-B, and less than 1% were culture, PCR, or antibody positive for SRV. In 1995 our original SPF colony is still negative for herpes-B and SRV. The percentage of herpes B positive animals in the remaining colony was 55%, very similar to 1994 results. None of the 792 animals surveyed this year were positive for SRV or STLV-I. Results are encouraging for the elimination of SRV from our Center breeding colonies, and future survey results will be used to monitor this condition.